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Abstract:

The present invention relates to a catalyst for producing a liquefied
petroleum gas, which is used for producing a liquefied petroleum gas
containing propane or butane as a main component by reacting carbon
monoxide and hydrogen, and comprises a Cu--Zn-based methanol synthesis
catalyst and a Cu-supported β-zeolite in which at least Cu is
supported on a β-zeolite.

Claims:

1. A catalyst for producing a liquefied petroleum gas, which is used for
producing a liquefied petroleum gas containing propane or butane as a
main component by reacting carbon monoxide and hydrogen, comprising A
Cu--Zn-based methanol synthesis catalyst; and A Cu-supported
β-zeolite in which at least Cu is supported on a β-zeolite.

2. The catalyst according to claim 1, wherein a ratio (by weight) of the
Cu--Zn-based methanol synthesis catalyst to the Cu-supported
β-zeolite [(Cu--Zn-based methanol synthesis catalyst)/(Cu-supported
β-zeolite)] is 0.1 to 5.

3. The catalyst according to claim 1, wherein the Cu--Zn-based methanol
synthesis catalyst is a composite oxide composed mainly of copper oxide
and zinc oxide, or a composite oxide composed mainly of copper oxide and
zinc and having at least one metal supported thereon.

5. The catalyst according to claim 3, wherein the Cu--Zn-based methanol
synthesis catalyst has Zr supported on the composite oxide.

6. The catalyst according to claim 5, wherein the amount of Zr in the
Cu--Zn-based methanol synthesis catalyst is 0.5 wt % to 8 wt %.

7. The catalyst according to claim 1, wherein the β-zeolite as a
support for the Cu-supported β-zeolite has a SiO2/Al2O3 ratio of 10
to 150.

8. The catalyst according to claim 1, wherein the amount of Cu in the
Cu-supported β-zeolite is 0.1 wt % to 15 wt %.

9. The catalyst according to claim 1, wherein the Cu-supported
β-zeolite has Cu and Zr supported on the β-zeolite.

10. The catalyst according to claim 9, wherein the amount of Zr in the
Cu-supported β-zeolite is 0.1 wt % to 5 wt %.

11. The catalyst according to claim 1, wherein the Cu--Zn-based methanol
synthesis catalyst is a composite oxide composed mainly of copper oxide
and zinc oxide on which Zr is supported in an amount of 0.5 wt % to 8 wt
%; and the Cu-supported β-zeolite is a β-zeolite with a
SiO2/Al2O3 ratio of 10 to 150 on which Cu is supported in
an amount of 0.1 wt % to 15 wt % and Zr is supported in an amount of 0.1
wt % to 5 wt %.

12. A process for producing a liquefied petroleum gas, comprising:
reacting carbon monoxide and hydrogen in the presence of the catalyst
according to claim 1, thereby producing a liquefied petroleum gas
containing propane or butane as a main component.

13. The process according to claim 12, wherein carbon monoxide and
hydrogen are reacted at a reaction temperature of 260.degree. C. to
325.degree. C.; a reaction pressure of 1.6 MPa to 4.5 MPa; and a contact
time between a starting gas, which contains carbon monoxide and hydrogen,
and the catalyst [W/F; ratio of the weight of the catalyst (W; g) to the
total flow rate of the starting gas (F; mol/h)] of 2 gh/mol to 20 gh/mol.

14. A process for producing a liquefied petroleum gas, comprising:
feeding a synthesis gas to a catalyst layer comprising the catalyst
according to Claim 1, thereby producing a liquefied petroleum gas
containing propane or butane as a main component.

15. A process for producing a liquefied petroleum gas, comprising:
producing a synthesis gas from a carbon-containing starting material and
at least one selected from the group consisting of H2O, O2 and
CO2; and feeding the synthesis gas to a catalyst layer comprising
the catalyst according to claim 1, thereby producing a liquefied
petroleum gas containing propane or butane as a main component.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a catalyst for producing a
liquefied petroleum gas containing propane or butane as a main component
by reacting carbon monoxide with hydrogen.

[0002] The present invention also relates to a process for producing a
liquefied petroleum gas containing propane or butane as a main component
from a synthesis gas, using the catalyst. The present invention also
relates to a process for producing a liquefied petroleum gas containing
propane or butane as a main component from a carbon-containing starting
material such as a natural gas, using the catalyst.

BACKGROUND ART

[0003] Liquefied petroleum gas (LPG) is a liquefied petroleum-based or
natural-gas-based hydrocarbon which is gaseous at an ambient temperature
under an atmospheric pressure by compression while optionally cooling.
The main component of LPG is propane or butane. LPG is advantageously
transportable because it can be stored or transported in a liquid form.
Thus, in contrast with a natural gas that requires a pipeline for supply,
it has a characteristic that it can be filled in a container to be
supplied to any place. For that reason, LPG comprising propane as a main
component, i.e. propane gas, has been widely used as a fuel for household
and business use. At present, propane gas is supplied to about 25 million
households (more than 50% of the total households) in Japan. In addition
to household and business use, LPG is used as a fuel for a portable
product such as a portable gas burner and a disposable lighter (mainly,
butane gas), an industrial fuel and an automobile fuel.

[0004] Conventionally, LPG has been produced by 1) collection from a wet
natural gas, 2) collection from a stabilization (vapor-pressure
regulating) process of crude petroleum, 3) separation and extraction of a
product in, for example, a petroleum refining process, or the like.

[0005] LPG, particularly propane gas which is used as a household/business
fuel, is expected to be in great demand in the future. Thus, it may be
very useful to establish an industrially practicable and new process for
producing LPG.

[0006] As a process for producing LPG, Patent document 1 discloses that a
synthesis gas consisting of hydrogen and carbon monoxide is reacted in
the presence of a mixed catalyst obtained by physically mixing a methanol
synthesis catalyst such as a Cu--Zn-based catalyst, a Cr--Zn-based
catalyst and a Pd-based catalyst, specifically a
CuO--ZnO--Al2O3 catalyst, a Pd/SiO2 catalyst or a
Cr--Zn-based catalyst with a methanol conversion catalyst composed of a
zeolite having an average pore size of about 10 Å (1 nm) or more,
specifically a Y-type zeolite, to provide a liquefied petroleum gas or a
mixture of hydrocarbons similar in composition to LPG. The catalyst
described in Patent document 1, however, does not necessarily have
sufficient performance.

[0007] As a process for producing LPG, Non-patent document 1 discloses
that a hybrid catalyst consisting of a methanol synthesis catalyst such
as a 4 wt % Pd/SiO2, a Cu--Zn--Al mixed oxide {Cu:Zn:Al=40:23:37
(atomic ratio)} or a Cu-based low-pressure methanol synthesis catalyst
(Trade name: BASF S3-85) and a high-silica Y-type zeolite with
SiO2/Al2O3=7.6, which has been subjected to treatment with
steam at 450° C. for 1 hour, can be used to produce C2 to C4
paraffins in a selectivity of 69 to 85% via methanol and dimethyl ether
from a synthesis gas. However, the catalyst described in Non-patent
document 1 may not have sufficient performance, as well as the catalyst
described in the above-mentioned Patent document 1.

[0008] As a catalyst for producing a liquefied petroleum gas which has
excellent catalyst performance, longer catalyst life, and reduced
deterioration over time, Patent document 2 discloses a catalyst
comprising a Pd-based methanol synthesis catalyst (catalyst in which 0.1
to 10 wt % of Pd is supported on a silica) and a β-zeolite. Patent
document 3 discloses a catalyst comprising a catalyst in which an
olefin-hydrogenation catalyst component is supported on a Zn--Cr-based
methanol synthesis catalyst (catalyst in which 0.005 to 5 wt % of Pd is
supported on a Zn--Cr-based methanol synthesis catalyst) and a
β-zeolite. However, Pd used in these catalysts for producing a
liquefied petroleum gas is very high-priced. Therefore, these catalysts
may be unfavorable in terms of cost.

[0009] In addition, Non-patent document 2 discloses that a hybrid catalyst
consisting of Pd--SiO2 or Pd, Ca--SiO2 as a methanol synthesis
catalyst, and a β-zeolite or a USY-type zeolite can be used to
produce LPG from a synthesis gas. In the catalyst described in Non-patent
document 2, however, the amount of Pd in Pd--SiO2 or Pd,
Ca--SiO2 is 4 wt %, and high-priced Pd is used in relatively large
quantities. Therefore, this catalyst may be also unfavorable in terms of
cost.

[0010] Patent document 4 discloses a catalyst comprising a Cu--Zn-based
methanol synthesis catalyst component and a β-zeolite catalyst
component in which preferably 0.1 to 1 wt % of Pd is supported on a
β-zeolite, which is described as a catalyst for producing a
liquefied petroleum gas which is suppressed in deterioration over time
and capable of serving as a catalyst in a reaction for producing a
liquefied petroleum gas from carbon monoxide and hydrogen under
relatively low temperature and pressure conditions. With regard to the
durability of the catalyst, Patent document 4 discloses that the catalyst
exhibits good activity (e.g., C3+C4 selectivity) for about 300 hours
(Example 2). However, in this Example, the temperature is controlled such
that the CO conversion is maintained at approximately 80% (the reaction
temperature is increased from 270° C. to 295° C. in
stepwise). Such a temperature control may be troublesome in a practical
process for producing LPG. In addition, this catalyst comprises
high-priced Pd. Therefore, this catalyst may be also unfavorable in terms
of cost.

[0017] An objective of the present invention is to provide a low-cost
catalyst for producing a liquefied petroleum gas, which enables the
production of a hydrocarbon containing propane or butane as a main
component, i.e. liquefied petroleum gas (LPG), with high activity, high
selectivity and high yield by reacting carbon monoxide and hydrogen, and
has a longer catalyst life with less deterioration over time.

[0018] Another objective of the present invention is to provide a process
for stably producing LPG, which has a high concentration of propane
and/or butane, from a synthesis gas with high yield for a long period,
using the catalyst. A further objective of the present invention is to
provide a process for stably producing LPG, which has a high
concentration of propane and/or butane, from a carbon-containing starting
material such as a natural gas with high yield for a long period.

Means for Solving the Problems

[0019] The present invention relates to the followings.

[0020] [1] A catalyst for producing a liquefied petroleum gas, which is
used for producing a liquefied petroleum gas containing propane or butane
as a main component by reacting carbon monoxide and hydrogen, comprising

[0021] a Cu--Zn-based methanol synthesis catalyst; and

[0022] a Cu-supported β-zeolite in which at least Cu is supported on
a β-zeolite.

[0023] [2] The catalyst for producing a liquefied petroleum gas as
described in [1], wherein a ratio (by weight) of the Cu--Zn-based
methanol synthesis catalyst to the Cu-supported β-zeolite
[(Cu--Zn-based methanol synthesis catalyst)/(Cu-supported
β-zeolite)] is 0.1 to 5.

[0024] [3] The catalyst for producing a liquefied petroleum gas as
described in any one of [1] to [2], wherein the Cu--Zn-based methanol
synthesis catalyst is a composite oxide containing copper oxide and zinc
oxide as a main component, or a composite oxide containing copper oxide
and zinc oxide as a main component and having at least one metal
supported thereon.

[0025] [4] The catalyst for producing a liquefied petroleum gas as
described in [3], wherein the composite oxide contains copper oxide and
zinc oxide and optionally aluminum oxide and/or chromium oxide in the
ratio (by weight) of (copper oxide):(zinc oxide):(aluminum
oxide):(chromium oxide)=100:(10 to 70):(0 to 60):(0 to 50).

[0026] [5] The catalyst for producing a liquefied petroleum gas as
described in any one of [3] to [4], wherein the Cu--Zn-based methanol
synthesis catalyst has Zr supported on the composite oxide.

[0027] [6] The catalyst for producing a liquefied petroleum gas as
described in [5], wherein the amount of Zr supported in the Cu--Zn-based
methanol synthesis catalyst is 0.5 wt % to 8 wt %.

[0028] [7] The catalyst for producing a liquefied petroleum gas as
described in any one of [1] to [6], wherein the β-zeolite as a
support for the Cu-supported β-zeolite has a
SiO2/Al2O3 ratio of 10 to 150.

[0029] [8] The catalyst for producing a liquefied petroleum gas as
described in any one of [1] to [7], wherein the amount of Cu supported in
the Cu-supported β-zeolite is 0.1 wt % to 15 wt %.

[0030] [9] The catalyst for producing a liquefied petroleum gas as
described in any one of [1] to [8], wherein the Cu-supported
β-zeolite has Cu and Zr supported on the β-zeolite.

[0031] [10] The catalyst for producing a liquefied petroleum gas as
described in [9], wherein the amount of Zr supported in the Cu-supported
β-zeolite is 0.1 wt % to 5 wt %.

[0032] [11] The catalyst for producing a liquefied petroleum gas as
described in any one of [1] to [10], wherein the Cu--Zn-based methanol
synthesis catalyst is a composite oxide containing copper oxide and zinc
oxide as a main component on which Zr is supported in an amount of 0.5 wt
% to 8 wt %; and the Cu-supported β-zeolite is a β-zeolite with
a SiO2/Al2O3 ratio of 10 to 150 on which Cu is supported
in an amount of 0.1 wt % to 15 wt % and Zr is supported in an amount of
0.1 wt % to 5 wt %.

[0034] reacting carbon monoxide and hydrogen in the presence of the
catalyst as described in any one of [1] to [11], whereby producing a
liquefied petroleum gas containing propane or butane as a main component.

[0035] [13] The process for producing a liquefied petroleum gas as
described in [12], wherein carbon monoxide and hydrogen are reacted at a
reaction temperature of 260° C. to 325° C.; a reaction
pressure of 1.6 MPa to 4.5 MPa; and a contact time between a starting
gas, which contains carbon monoxide and hydrogen, and the catalyst [W/F;
ratio of the weight of the catalyst (W; g) to the total flow rate of the
starting gas (F; mol/h)] of 2 gh/mol to 20 gh/mol.

[0036] [14] A process for producing a liquefied petroleum gas, comprising
a step of feeding a synthesis gas to a catalyst layer comprising the
catalyst as described in any one of [1] to [11], whereby producing a
liquefied petroleum gas containing propane or butane as a main component.

[0038] (1) a step of producing a synthesis gas from a carbon-containing
starting material and at least one selected from the group consisting of
H2O, O2 and CO2; and

[0039] (2) a step of producing a liquefied petroleum gas wherein the
synthesis gas is fed to a catalyst layer comprising the catalyst as
described in any one of [1] to [11], whereby producing a liquefied
petroleum gas containing propane or butane as a main component.

[0040] The term "synthesis gas" as used herein is a mixed gas comprising
hydrogen and carbon monoxide, and is not limited to a mixed gas
consisting of hydrogen and carbon monoxide. A synthesis gas may be, for
example, a mixed gas comprising carbon dioxide, water, methane, ethane,
ethylene and so on. A synthesis gas produced by reforming a natural gas
generally contains, in addition to hydrogen and carbon monoxide, carbon
dioxide and water vapor. A synthesis gas may be a coal gas produced by
coal gasification, or a water gas produced from a coal coke.

Effect of the Invention

[0041] When carbon monoxide and hydrogen are reacted in the presence of a
catalyst comprising a methanol synthesis catalyst component and a zeolite
catalyst component, the reaction represented by the following formula (I)
may proceed to form a hydrocarbon containing propane or butane as a main
component, i.e. liquefied petroleum gas (LPG).

##STR00001##

[0042] First, on the methanol synthesis catalyst component, methanol is
formed from carbon monoxide and hydrogen. Simultaneously, dimethyl ether
is also formed by dehydro-dimerization of methanol. Then, methanol thus
formed is converted to a lower-olefin hydrocarbon comprising propylene or
butene as a main component at an active site in a pore in the zeolite
catalyst component. In the reaction, methanol would be dehydrated to form
a carbene (H2C:), which is subjected to polymerization to form a
lower olefin. The lower olefin thus formed is released from the pore in
the zeolite catalyst component and rapidly hydrogenated on the methanol
synthesis catalyst component, to form a paraffin comprising propane or
butane as a main component, i.e. LPG.

[0043] The term "methanol synthesis catalyst component" as used herein
refers to a compound which can act as a catalyst in the reaction of
CO+2H2→CH3OH. The term "zeolite catalyst component" as
used herein refers to a zeolite which can act as a catalyst in a
condensation reaction of methanol into a hydrocarbon and/or a
condensation reaction of dimethyl ether into a hydrocarbon. Additionally,
the methanol synthesis catalyst component is required to act as a
catalyst in a hydrogenation reaction of an olefin into a paraffin.

[0044] According to the present invention, a methanol synthesis catalyst
component to be used is a Cu--Zn-based methanol synthesis catalyst, and a
zeolite catalyst component to be used is a Cu-supported β-zeolite in
which Cu is supported on a β-zeolite. When combining a Cu--Zn-based
methanol synthesis catalyst with a Cu-supported β-zeolite, LPG
(propane, butane) may be produced at a temperature of from 260° C.
to 325° C., preferably at a temperature equal to or lower than
300° C., more preferably at a temperature equal to or lower than
290° C., with high activity, high selectivity and high yield,
which is equal to or higher than a conventional catalyst. In addition,
the catalyst for producing a liquefied petroleum gas according to the
present invention has reduced deterioration over time, and a longer
catalyst life. The catalyst of the present invention has much higher
stability and durability, as compared with a conventional catalyst.

[0045] Accordingly, when using the catalyst for producing a liquefied
petroleum gas according to the present invention, propane and/or butane,
i.e. LPG, may be produced with high activity and high yield for a longer
period.

[0046] Moreover, any conventional catalyst for producing a liquefied
petroleum gas which has excellent performance comprises high-priced Pd.
In contrast, the catalyst of the present invention does not comprise Pd.
Thus, the catalyst of the present invention is more inexpensive than
conventional catalysts.

[0047] A Cu-supported β-zeolite to be used in the present invention
may have a metal other than Cu, for example, Zr, which is supported on
the zeolite. A Cu--Zn-based methanol synthesis catalyst to be used in the
present invention may be selected, without limitation, from those which
contains Cu and Zn, and can act as a catalyst in the reaction:
CO+2H2CH3OH. The common Cu--Zn-based methanol synthesis
catalysts are a composite oxide composed mainly of copper oxide and zinc
oxide (Cu--Zn composite oxide), and a composite oxide composed mainly of
copper oxide and zinc oxide and containing aluminum oxide and/or chromium
oxide and/or other metal oxides as an additive component (for example,
Cu--Zn--Al composite oxide and Cu--Zn--Cr composite oxide). According to
the present invention, catalysts in which a metal such as Zr is supported
on these common Cu--Zn-based methanol synthesis catalysts, as well as
common Cu--Zn-based methanol synthesis catalysts, may be suitably used.

[0048] According to the present invention, a preferable catalyst may be
the combination of a methanol synthesis catalyst component in which Zr is
supported in an amount of 0.5 wt % to 8 wt % on a Cu--Zn-based methanol
synthesis catalyst such as Cu--Zn composite oxide, Cu--Zn--Al composite
oxide and Cu--Zn--Cr composite oxide; and a zeolite catalyst component in
which Cu is supported in an amount of 0.1 wt % to 15 wt % and Zr is
supported in an amount of 0.1 wt % to 5 wt % on a β-zeolite,
preferably a β-zeolite with a SiO2/Al2O3 ratio of 10
to 150, because the stability of the catalyst may be greatly improved,
while maintaining high activity and high selectivity.

[0049] The reaction conditions are also important for stably producing LPG
for a long period with high conversion, high selectivity and high yield.
The present invention may be particularly effective when carbon monoxide
and hydrogen are reacted in the presence of the catalyst of the present
invention at a reaction temperature of 260° C. to 325° C.;
a reaction pressure of 1.6 MPa to 4.5 MPa; and W/F of 7 gh/mol to 20
gh/mol.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG. 1 is a process flow diagram showing a main configuration in an
example of an LPG producing apparatus suitable for conducting the process
for LPG production according to the present invention.

[0051] FIG. 2 is a graph showing the results of the LPG synthesis
reactions at various reaction temperatures using a (Cu--Zn+0.5%
Cu-β-37) catalyst in Example 1.

[0052] FIG. 3 is a graph showing the results of the LPG synthesis
reactions at various reaction temperatures using a (Cu--Zn+0.5%
Cu-β-350) catalyst in Example 2.

[0053] FIG. 4 is a graph showing the results of the LPG synthesis
reactions at various reaction temperatures using a (Cu--Zn+5.0%
Cu/β-37) catalyst in Example 3.

[0054] FIG. 5 is a graph showing the results of the LPG synthesis
reactions at various reaction temperatures using a (Cu--Zn+10%
Cu/β-37) catalyst in Example 4.

[0055] FIG. 6 is a graph showing the results of the LPG synthesis
reactions at various reaction pressures using a (Cu--Zn+5.0%
Cu/β-37) catalyst in Example 5.

[0056] FIG. 7 is a graph showing the results of the LPG synthesis
reactions at various W/Fs using a (Cu--Zn+5.0% Cu/β-37) catalyst in
Example 6.

[0057] FIG. 8 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
(Cu--Zn+5.0% Cu/β-37) catalyst in Example 7.

[0058] FIG. 9 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
(Cu--Zn+10% Cu/β-37) catalyst in Example 8.

[0059] FIG. 10 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
(Cu--Zn+2.0% Cu/β-37) catalyst in Example 9.

[0060] FIG. 11 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
[Cu--Zn+(5.0% Cu+2.5% Zn)/β-371 catalyst in Example 10.

[0061] FIG. 12 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
[Cu--Zn+(5.0% Cu+2.5% Zr)/β-37] catalyst in Example 11.

[0062] FIG. 13 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
[(Cu--Zn+2.5% Cr)+(5.0% Cu+2.5% Zr)/β-37] catalyst in Example 12.

[0063] FIG. 14 is a graph showing the result (change in the conversion of
carbon monoxide into hydrocarbon (CH), the conversion of carbon monoxide
into carbon dioxide by shift reaction, and the composition of the
synthesized hydrocarbon over time) of the LPG synthesis reaction using a
[(Cu--Zn+2.5% Zr)+(5.0% Cu+2.5% Zr)/β-37] catalyst in Example 13.

1. Catalyst for Producing a Liquefied Petroleum Gas According to the
Present Invention

[0069] A catalyst for producing a liquefied petroleum gas according to the
present invention comprises at least one Cu--Zn-based methanol synthesis
catalyst, and at least one Cu-supported β-zeolite in which at least
Cu is supported on a β-zeolite.

[0070] A catalyst for producing a liquefied petroleum gas of the present
invention may comprise other additive components as long as its intended
effect would not be impaired.

[0071] A ratio of the Cu--Zn-based methanol synthesis catalyst to the
Cu-supported β-zeolite (Cu--Zn-based methanol synthesis
catalyst/Cu-supported β-zeolite; by weight) is preferably 0.1 or
more, more preferably 0.5 or more. A ratio of the Cu--Zn-based methanol
synthesis catalyst to the Cu-supported β-zeolite (Cu--Zn-based
methanol synthesis catalyst/Cu-supported β-zeolite; by weight) is
preferably 5 or less, more preferably 3 or less. When a ratio of the
Cu--Zn-based methanol synthesis catalyst to the Cu-supported
β-zeolite is controlled to within the above range, propane and/or
butane may be produced with higher selectivity and higher yield.

[0072] A Cu--Zn-based methanol synthesis catalyst as a methanol synthesis
catalyst component acts as a methanol synthesis catalyst and a
hydrogenation catalyst for an olefin. A Cu-supported β-zeolite as a
zeolite catalyst component acts as a solid acid zeolite catalyst, whose
acidity is adjusted, in a condensation reaction of methanol and/or of
dimethyl ether into hydrocarbon. A ratio of the methanol synthesis
catalyst component to the zeolite catalyst component is, therefore,
reflected in a relative ratio of the ability to form methanol and the
ability to hydrogenate an olefin to the ability to form a hydrocarbon
from methanol in the catalyst of the present invention has. In the
present invention, when reacting carbon monoxide and hydrogen to produce
a liquefied petroleum gas comprising propane or butane as a main
component, carbon monoxide and hydrogen must be sufficiently converted
into methanol by the action of a methanol synthesis catalyst component,
and methanol produced must be sufficiently converted, by the action of a
zeolite catalyst component, into an olefin comprising propylene or butene
as a main component, which must be converted into a liquefied petroleum
gas comprising propane or butane as a main component by the action of a
methanol synthesis catalyst component.

[0073] When a ratio of the Cu--Zn-based methanol synthesis catalyst to the
Cu-supported β-zeolite (Cu--Zn-based methanol synthesis
catalyst/Cu-supported β-zeolite; by weight) is 0.1 or more, more
preferably 0.5 or more, carbon monoxide and hydrogen may be converted
into methanol with higher conversion. In addition, when a ratio of the
Cu--Zn-based methanol synthesis catalyst to the Cu-supported
β-zeolite (Cu--Zn-based methanol synthesis catalyst/Cu-supported
β-zeolite; by weight) is 0.8 or more, methanol produced may be
converted into a liquefied petroleum gas comprising propane or butane as
a main component with higher selectivity.

[0074] On the other hand, when a ratio of the Cu--Zn-based methanol
synthesis catalyst to the Cu-supported β-zeolite (Cu--Zn-based
methanol synthesis catalyst/Cu-supported β-zeolite; by weight) is 5
or less, more preferably 3 or less, methanol produced may be converted
into a liquefied petroleum gas comprising propane or butane as a main
component with higher conversion.

[0075] A ratio of the Cu--Zn-based methanol synthesis catalyst to the
Cu-supported β-zeolite is not limited to the above range, and may be
appropriately determined, depending on the types of a methanol synthesis
catalyst component and a zeolite catalyst component, and the like.

[0077] A methanol synthesis catalyst component to be used in the present
invention is a Cu--Zn-based methanol synthesis catalyst,

[0078] A Cu--Zn-based methanol synthesis catalyst to be used may be
selected, without limitation, from those which contains Cu and Zn, and
can act as a catalyst in the reaction: CO+2H2→CH3OH, and
any known Cu--Zn-based methanol synthesis catalyst may be used. A
commercially available Cu--Zn-based methanol synthesis catalyst may be
also used.

[0080] A Cu--Zn-based methanol synthesis catalyst to be used in the
present invention may preferably contain copper oxide and zinc oxide and
optionally aluminum oxide and chromium oxide in the ratio (by weight) of
(copper oxide):(zinc oxide):(aluminum oxide):(chromium oxide)=100:(10 to
70):(0 to 60):(0 to 50), more preferably (copper oxide)=(zinc oxide)
(aluminum oxide):(chromium oxide)=100:(20 to 60):(0 to 40):(0 to 40).
When using a Cu--Zn-based methanol synthesis catalyst having a ratio of
oxides within the above range, higher catalytic activity may be achieved,
and propane and/or butane may be produced with higher conversion, higher
selectivity and higher yield.

[0081] According to the present invention, not only commonly-used
Cu--Zn-based methanol synthesis catalysts as described above but also
catalysts in which at least one metal is supported on these commonly-used
Cu--Zn-based methanol synthesis catalysts may be used. The metal is
preferably supported on a Cu--Zn-based methanol synthesis catalyst (a
composite oxide composed mainly of copper oxide and zinc oxide) in a
highly dispersed manner.

[0082] A particularly preferable metal-supported Cu--Zn-based methanol
synthesis catalyst may be a catalyst in which Zr is supported on a
Cu--Zn-based methanol synthesis catalyst as described above (a composite
oxide composed mainly of copper oxide and zinc oxide, which may
optionally contain aluminum oxide, chromium oxide and so on). When using
a Zr-supported Cu--Zn-based methanol synthesis catalyst in combination
with a Cu-supported β-zeolite, particularly a Cu, Zr-supported
β-zeolite in which Cu and Zr are supported on a β-zeolite, the
stability and durability of the catalyst may be greatly improved.

[0083] A supported metal such as Zr may not be necessarily contained as a
metal, and may be contained in the form of an oxide, a nitrate, a
chloride and the like. In such a case, prior to the reaction, the
catalyst may be subjected to reduction by hydrogen, for example, to
convert the supported metal into a metal or a metal oxide, if necessary.

[0084] The amount of the supported Zr in the Cu--Zn-based methanol
synthesis catalyst is preferably 0.5 wt % or more, more preferably 1 wt %
or more, particularly preferably 1.5 wt % or more. In addition, the
amount of the supported Zr in the Cu--Zn-based methanol synthesis
catalyst is preferably 8 wt % or less, more preferably 5 wt % or less, in
the light of dispersibility and economical efficiency.

[0085] The methanol synthesis catalyst component as described above
(Zr-supported Cu--Zn-based methanol synthesis catalyst) may be a
Cu--Zn-based methanol synthesis catalyst on which another component, in
addition to Zr, is supported as long as the desired effects of the
catalyst are maintained.

[0086] The Cu--Zn-based methanol synthesis catalyst (including
metal-supported Cu--Zn-based methanol synthesis catalyst) may be used
alone or in combination of two or more.

[0087] A Cu--Zn-based methanol synthesis catalyst such as Cu--Zn composite
oxide, Cu--Zn--Al composite oxide and Cu--Zn--Cr composite oxide may be
prepared by a known method such as a precipitation method. A
metal-supported Cu--Zn-based methanol synthesis catalyst such as
Zr-supported Cu--Zn-based methanol synthesis catalyst may be prepared by
carrying a metal such as Zr or a metal compound onto a Cu--Zn-based
methanol synthesis catalyst, which may be prepared by a precipitation
method and the like, or commercially available, by a known method such as
an impregnation method.

[0088] (Zeolite Catalyst Component; Cu-Supported β-Zeolite)

[0089] A zeolite catalyst component to be used in the present invention is
a Cu-supported fβ-zeolite in which at least Cu is supported on a
β-zeolite.

[0090] Cu may not be necessarily contained as a metal, and may be
contained in the form of an oxide, a nitrate, a chloride and the like. In
such a case, in order to achieve higher catalytic activity, the catalyst
may be preferably subjected to reduction by hydrogen, for example, to
convert Cu into metallic copper, prior to the reaction. The reduction
treatment condition to activate Cu may be appropriately determined.

[0091] In addition, Cu is preferably supported on a β-zeolite in a
highly dispersed manner.

[0092] The amount of the supported Cu in the Cu-supported β-zeolite
is preferably 0.1 wt % or more, more preferably 1 wt % or more,
particularly preferably 3 wt % or more. In addition, the amount of the
supported Cu in the Cu-supported β-zeolite is preferably 15 wt % or
less, more preferably 10 wt % or less, particularly preferably 8 wt % or
less. When the amount of the supported Cu in the Cu-supported
β-zeolite is within the above range, propane and/or butane may be
stably produced with higher conversion, higher selectivity and higher
yield for a longer period. A substantial amount of Cu must be supported
on a β-zeolite to achieve the remarkable effect of the present
invention. However, when the amount of the supported Cu in the
Cu-supported β-zeolite is excessively high, the catalytic activity
may rapidly decrease.

[0093] The β-zeolite as a support for the Cu-supported β-zeolite
is preferably, but not limited to, a β-zeolite with a
SiO2/Al2O3 ratio of 10 to 150. When using a β-zeolite
with a SiO2/Al2O3 ratio of 10 to 150, higher catalytic
activity and higher selectivity for propane and butane may be achieved.
The SiO2/Al2O3 ratio of β-zeolite is more preferably
100 or less, particularly preferably 50 or less. In addition, the
SiO2/Al2O3 ratio of β-zeolite is more preferably 20
or more, particularly preferably 30 or more.

[0094] The β-zeolite may contain an element other than Si and Al in
the lattice.

[0095] The Cu-supported β-zeolite to be used in the present invention
may have at least one other metal together with Cu, which is supported on
the β-zeolite. When a certain metal, together with Cu, is supported
on a β-zeolite, Cu may be more stably supported on the
fβ-zeolite.

[0096] Specific examples of the supported metal or metal compound may
include Zr, Zn, Cr, Ni, Mo and Co. In the light of cost, it is not
preferred that a noble metal including Pd is supported on the
β-zeolite, as described above, although a small amount of Pd in
addition to Cu may be supported on the β-zeolite.

[0097] A particularly preferable supported metal may be Zr. When Zr in
addition to Cu is supported on a β-zeolite, the stability and
durability of the catalyst may be further improved, while maintaining
high activity and high selectivity for propane and butane.

[0098] In the case where Cu and Zr are supported on a β-zeolite, the
amount of the supported Zr is preferably 0.1 wt % or more, more
preferably 1 wt % or more, particularly preferably 2 wt % or more. When
the amount of the supported Zr is within the above range, the stability
and durability of the catalyst may be sufficiently improved.

[0099] In addition, the amount of the supported Zr is preferably 5 wt % or
less, more preferably 3 wt % or less. An excessively large amount of the
supported Zr may lead to lower activity and lower selectivity for LPG.

[0100] A particularly preferable Cu-supported β-zeolite to be used in
the present invention may be a β-zeolite with a
SiO2/Al2O3 ratio of 10 to 150, more preferably 10 to 50,
on which Cu is supported in an amount of 0.1 wt % to 15 wt % and Zr is
supported in an amount of 0.1 wt % to 5 wt %.

[0101] According to the present invention, the Cu-supported β-zeolite
may be a β-zeolite on which another component, in addition to Cu, or
Cu and Zr, is supported as long as the desired effects of the catalyst
are maintained.

[0102] The Cu-supported β-zeolite (including Cu-supported
β-zeolite in which a metal other than Cu is supported on a
β-zeolite) may be used alone or in combination of two or more.

[0103] A Cu-supported β-zeolite in which Cu and optionally Zr and
other metals are supported on a β-zeolite may be prepared by
carrying a metal such as Cu and Zr onto a β-zeolite by a known
method such as an impregnation method and an ion exchange method. A
β-zeolite may be prepared by a known method, and may be commercially
available.

2. Process for Producing a Catalyst for Producing a Liquefied Petroleum
Gas According to the Present Invention

[0104] A catalyst for producing a liquefied petroleum gas according to the
present invention is preferably produced by separately preparing a
Cu--Zn-based methanol synthesis catalyst as a methanol synthesis catalyst
component and a Cu-supported β-zeolite as a zeolite catalyst
component, and then mixing them. By separately preparing a methanol
synthesis catalyst component and a zeolite catalyst component, a
composition, a structure and a property of each component may be easily
optimized for each function.

[0105] A Cu--Zn-based methanol synthesis catalyst may be prepared by a
known method, as described above. A commercially available Cu--Zn-based
methanol synthesis catalyst may be also used.

[0106] Some of methanol synthesis catalyst components must be activated by
reduction treatment before use. In the present invention, it is not
necessarily required to activate a methanol synthesis catalyst component
by reduction treatment in advance. The methanol synthesis catalyst
component may be activated by subjecting the catalyst for producing a
liquefied petroleum gas of the present invention to the reduction
treatment, before the beginning of the reaction, after producing the
catalyst by mixing a methanol synthesis catalyst component and a zeolite
catalyst component, and then molding the mixture. The reduction treatment
condition may be determined, depending on some factors such as the type
of the methanol synthesis catalyst component, as appropriate.

[0107] A Cu-supported β-zeolite as a zeolite catalyst component may
be prepared by a known method, as described above.

[0108] A catalyst for producing a liquefied petroleum gas according to the
present invention may be produced by homogeneously mixing a methanol
synthesis catalyst component and a zeolite catalyst component, and then,
if necessary, molding the mixture. A procedure of mixing and molding
these catalyst components is preferably, but not limited to, a dry
method. When mixing and molding these catalyst components by a wet
method, there may occur a compound transfer between these catalyst
components, for example, neutralization due to transfer of a basic
component in a methanol synthesis catalyst component to an acidic site in
a zeolite catalyst component, leading to the change in properties, which
have been optimized for each function of these catalyst components, and
the like. A catalyst may be molded by an extrusion method and a
tablet-compression method, for example.

[0109] According to the present invention, a methanol synthesis catalyst
component and a zeolite catalyst component to be mixed may preferably
have a relatively large particle size; specifically a particle size of
100 μm or more. A catalyst for producing a liquefied petroleum gas
according to the present invention, which is prepared by mixing a
methanol synthesis catalyst component with a particle size of 100 μm
or more and a zeolite catalyst component with a particle size of 100
μm or more, and then, if necessary, molding the mixture, may have
higher catalytic activity and higher yield of LPG, as compared with a
catalyst which is prepared by mixing a methanol synthesis catalyst
component with a smaller particle size and a zeolite catalyst component
with a smaller particle size.

[0110] The particle sizes of a methanol synthesis catalyst component and a
zeolite catalyst component to be mixed are more preferably 200 μm or
more, particularly preferably 500 μm or more. On the other hand, the
particle sizes of a methanol synthesis catalyst component and a zeolite
catalyst component to be mixed are preferably 5 mm or less, more
preferably 3 mm or less so as to maintain the excellent performance of
the mixed catalyst of the present invention.

[0111] It is preferred that a methanol synthesis catalyst component and a
zeolite catalyst component to be mixed have the same particle size.

[0112] In general, each catalyst component is, if necessary, mechanically
pulverized to the same particle size of about 0.5 μm to about 2 μm,
for example, and then the catalyst components are homogeneously mixed and
molded, if necessary, to prepare a mixed catalyst. Alternatively, all of
catalyst components are placed into a vessel, and are mixed, while
mechanically pulverizing, to prepare a homogeneous mixture with a
particle size of about 0.5 μm to about 2 μm, for example, and then
the mixture is molded, if necessary.

[0113] In contrast, when preparing a catalyst for producing a liquefied
petroleum gas according to the present invention by mixing a methanol
synthesis catalyst component with a particle size of 100 μm or more
and a zeolite catalyst component with a particle size of 100 μm or
more, the catalyst may be generally produced as follows. Each catalyst
component is molded by a known molding method such as a
tablet-compression and an extrusion, and then, if necessary, mechanically
pulverized to the same particle size of preferably about 100 μm to
about 5 mm. And then, these components are homogeneously mixed. If
necessary, the mixture is molded again to prepare a catalyst for
producing a liquefied petroleum gas of the present invention.

3. Process for Producing a Liquefied Petroleum Gas

[0114] Next, there will be described a process for producing a liquefied
petroleum gas comprising propane or butane, preferably propane, as a main
component in which carbon monoxide and hydrogen are reacted using a
catalyst for producing a liquefied petroleum gas according to the present
invention as described above.

[0115] A reaction temperature is preferably 260° C. or higher, more
preferably 270° C. or higher, particularly preferably 275°
C. or higher. By controlling a reaction temperature within the above
range, higher catalytic activity and higher selectivity for LPG may be
achieved, and therefore propane and/or butane may be produced with higher
yield.

[0116] On the other hand, a reaction temperature is preferably 325°
C. or lower, more preferably 315° C. or lower, particularly
preferably 310° C. or lower, in the light of the stability and
durability of the catalyst.

[0117] A reaction pressure is preferably 1.6 MPa or higher, more
preferably 1.8 MPa or higher, particularly preferably 1.9 MPa or higher,
in the light of the higher catalytic activity.

[0118] On the other hand, a reaction pressure is preferably 4.5 MPa or
lower, more preferably 4 MPa or lower, in the light of higher selectivity
for LPG.

[0119] As for a contact time between a starting gas, which contains carbon
monoxide and hydrogen, and the catalyst, W/F [ratio of the weight of the
catalyst (W; g) to the total flow rate of the starting gas (F; mol/h)] is
preferably 2 gh/mol or more, more preferably 4 gh/mol or more, in the
light of higher conversion of carbon monoxide and higher selectivity for
LPG. On the other hand, W/F is preferably 20 gh/mol or less, more
preferably 16 gh/mol or less, in the light of economical efficiency.

[0120] A concentration of carbon monoxide in a gas fed into a reactor is
preferably 20 mol % or more, more preferably 25 mol % or more, in the
light of ensuring a pressure (partial pressure) of carbon monoxide
required for the reaction, and improving a specific productivity of the
materials. In addition, a concentration of carbon monoxide in a gas fed
into a reactor is preferably 45 mol % or less, more preferably 40 mol %
or less, in the light of a further sufficiently high conversion of carbon
monoxide.

[0121] A concentration of hydrogen in a gas fed into a reactor is
preferably 1.2 moles or more, more preferably 1.5 moles or more per one
mole of carbon monoxide, in order that carbon monoxide may react more
sufficiently. In addition, a concentration of hydrogen in a gas fed into
a reactor is preferably 3 moles or less, more preferably 2.5 moles or
less per one mole of carbon monoxide, in the light of economical
efficiency.

[0122] A gas fed into a reactor may contain carbon dioxide in addition to
carbon monoxide and hydrogen, which are starting materials of the
reaction. By recycling carbon dioxide discharged from the reactor, or by
adding the corresponding amount of carbon dioxide, formation of carbon
dioxide from carbon monoxide by a shift reaction in the reactor may be
substantially reduced or be eliminated.

[0123] A gas fed into a reactor may contain water vapor. In addition, a
gas fed into a reactor may contain an inert gas such as Ar, and the like.

[0124] A gas fed into a reactor may be dividedly fed to the reactor,
thereby controlling a reaction temperature.

[0125] The reaction may be conducted in a fixed bed, a fluidized bed, a
moving bed, a slurry bed, or the like. The reaction may be conducted in a
vapor phase, a liquid phase, or a supercritical phase. The reaction mode
and the reactor to be used may be preferably selected, taking both of
control of a reaction temperature and a regeneration method of the
catalyst into account. Examples of the reactor with a fixed bed may
include a quench type reactor such as an internal multistage quench type,
a multitubular type reactor, a multistage type reactor having a plurality
of internal heat exchangers or the like, a multistage cooling radial flow
type reactor, a double pipe heat exchange type reactor, an internal
cooling coil type reactor, a mixed flow type reactor, and other types of
reactors.

[0126] The catalyst for producing a liquefied petroleum gas according to
the present invention may be diluted with silica, alumina or an inert
stable heat conductor and used in order to control a reaction
temperature. In addition, the catalyst for producing a liquefied
petroleum gas according to the present invention may be applied to the
surface of a heat exchanger and used in order to control a reaction
temperature.

4. Process for Producing a Liquefied Petroleum Gas from a
Carbon-Containing Starting Material

[0127] According to the present invention, a synthesis gas may be used as
a starting gas for producing a liquefied petroleum gas (LPG).

[0128] Next, with reference to the drawing, there will be described an
embodiment of a process for producing LPG according to the present
invention, which comprises producing a synthesis gas from a
carbon-containing starting material (synthesis gas production process)
and then producing LPG from the obtained synthesis gas using a catalyst
of the present invention (liquefied petroleum gas production process).

[0129] FIG. 1 shows an embodiment of an LPG production apparatus suitable
for carrying out a production process for LPG according to the present
invention.

[0130] First, a natural gas (methane) as a carbon-containing starting
material is fed into a reformer 1 via a line 3. In addition, for steam
reforming, steam (not shown) is also fed into the line 3. In the reformer
1, there is a reforming catalyst layer 1a comprising a reforming catalyst
(a catalyst for producing a synthesis gas). The reformer 1 also has a
heating means for supplying heat required for reforming (not shown). In
the reformer 1, methane is reformed in the presence of the reforming
catalyst to produce a synthesis gas containing hydrogen and carbon
monoxide.

[0131] The synthesis gas thus produced is fed into a reactor 2 via a line
4. In the reactor 2, there is a catalyst layer 2a comprising a catalyst
of the present invention. In the reactor 2, a hydrocarbon gas containing
propane or butane as a main component (a lower-paraffin-containing gas)
is produced from the synthesis gas in the presence of the catalyst of the
present invention.

[0132] The hydrocarbon gas thus produced is pressurized and cooled, after
optional removal of water and the like, and LPG, which is a product, is
obtained from a line 5. Optionally, hydrogen and the like may be removed
from the LPG by gas-liquid separation, for example.

[0133] A low-boiling component and the like may be separated, by a known
method, from the hydrocarbon gas produced in the reactor 2 and recycled
into the reformer 1 as a starting material for the synthesis gas
production process (reforming process).

[0134] A gas obtained by adding carbon dioxide and the like to the
synthesis gas produced in the reformer 1 may be fed into the reactor 2.
Alternatively, a gas obtained by adding additional hydrogen or carbon
monoxide to the synthesis gas produced in the reformer 1 may be fed into
the reactor 2. A gas obtained by adjusting its composition by a shift
reaction may be fed into the reactor 2.

[0135] The LPG production apparatus may be, as necessary, provided with a
booster, a heat exchanger, a valve, an instrumentation controller and so
on, which are not shown.

[0136] <Synthesis Gas Production Process>

[0137] In a synthesis gas production process, a synthesis gas is produced
from a carbon-containing starting material and at least one selected from
the group consisting of H2O, O2 and CO2.

[0138] A carbon-containing substance, which can react with at least one
selected from the group consisting of H2O, O2 and CO2 to
form H2 and CO, may be used as a carbon-containing starting
material. A substance known as a raw material for a synthesis gas may be
used as a carbon-containing starting material; for example, lower
hydrocarbons such as methane and ethane, a natural gas, a naphtha, a
coal, and the like may be used.

[0139] According to the present invention, a catalyst is generally used in
a synthesis gas production process and a liquefied petroleum gas
production process. Therefore, a carbon-containing starting material (a
natural gas, a naphtha, a coal and so on) preferably contains less
catalyst poisoning components such as sulfur and a sulfur compound. When
a carbon-containing starting material contains a catalyst poisoning
component, a step of removing the catalyst poisoning component such as
devulcanization may be conducted before a synthesis gas production
process, if necessary.

[0140] A synthesis gas may be produced by reacting the carbon-containing
starting material as described above with at least one selected from the
group consisting of H2O, O2 and CO2 in the presence of a
catalyst for producing a synthesis gas (reforming catalyst).

[0141] A synthesis gas may be produced by a known method. When a natural
gas (methane) is used as a starting material, for example, a synthesis
gas may be produced by a water vapor reforming method, an autothermal
reforming method, and the like. In these methods, water vapor required
for a water-vapor reforming, oxygen required for an autothermal
reforming, and the like may be fed, if necessary. When a coal is used as
a starting material, a synthesis gas may be produced using an aerating
gasification furnace, and the like.

[0142] A shift reactor, for example, may be provided downstream of a
reformer, which is a reactor for producing a synthesis gas from the
starting materials as described above, so that a synthesis gas
composition may be adjusted by a shift reaction
(CO+H2O→CO2+H2).

[0143] In the present invention, a preferable composition of a synthesis
gas produced in a synthesis gas production process is a molar ratio of
H2/CO is 7/3≈2.3 in terms of the stoichiometry for a lower
paraffin production, and a ratio of hydrogen to carbon monoxide
(H2/CO; by mole) in a synthesis gas produced is preferably 1.2 to 3.
A ratio of hydrogen to carbon monoxide (H2/CO; by mole) in a
synthesis gas is preferably 1.2 or more, more preferably 1.5 or more, in
that carbon monoxide may react suitably, because hydrogen is generated by
a shift reaction caused by water, which is generated in a conversion
reaction from a synthesis gas to LPG. It is preferred that hydrogen is
fed only in an amount such that carbon monoxide may react suitably to
form a liquefied petroleum gas comprising propane or butane as a main
component, and excessive hydrogen may increase the total pressure of a
starting gas unnecessarily, leading to a lower economical efficiency.
Thus, a ratio of hydrogen to carbon monoxide (H2/CO; by mole) in a
synthesis gas is preferably 3 or less, more preferably 2.5 or less.

[0144] A concentration of carbon monoxide in a synthesis gas produced is
preferably 20 mol % or more, more preferably 25 mol % or more, in the
light of ensuring a pressure (partial pressure) of carbon monoxide
suitable for a conversion reaction from a synthesis gas to LPG, and
improving a specific productivity of the materials. In addition, a
concentration of carbon monoxide in a synthesis gas produced is
preferably 45 mol % or less, more preferably 40 mol % or less, in the
light of a further sufficiently high conversion of carbon monoxide in a
conversion reaction from a synthesis gas to LPG.

[0145] A synthesis gas having the composition as described above may be
produced by appropriately selecting reaction conditions such as a feeding
ratio of a carbon-containing starting material and at least one material
selected from the group consisting of steam (water), oxygen and carbon
dioxide, a kind of a catalyst for producing a synthesis gas to be used,
and the like.

[0146] For example, a synthesis gas may be produced using a gas whose
composition is steam/methane (molar ratio) of 1 and carbon
dioxide/methane (molar ratio) of 0.4 as a starting gas under the
operation conditions of a reaction temperature (an outlet temperature of
a catalyst layer) of 800 to 900° C., a reaction pressure of 1 to 4
MPa, a gas space velocity (GHSV) of 2000 hr-1, in an external
heating multitubular tubular-reactor type apparatus filled with a
catalyst, a Ru or Rh/a sintered magnesia having the smaller surface area.

[0147] When using steam for reforming in a synthesis gas production, a
ratio of steam/raw material carbon (S/C) is preferably 1.5 or less, more
preferably 0.8 to 1.2, in the light of an energy efficiency. Meanwhile,
such a low SIC value may lead to the considerable possibility of carbon
precipitation formation.

[0148] When producing a synthesis gas with a low S/C, it may be preferable
to use a catalyst which have a good activity of forming a synthesis gas
and a low activity of forming a carbon precipitation, as described in,
for example, WO 98/46524, JP-A-2000-288394 and JP-A-2000-469.
Hereinafter, such a catalyst will be described.

[0149] The catalyst described in WO 98/46524 is a catalyst in which at
least one catalyst metal selected from rhodium, ruthenium, iridium,
palladium and platinum is supported on a support composed of a metal
oxide, which has a specific surface area of 25 m2/g or less, an
electronegativity of a metal ion in the support metal oxide of 13.0 or
less, and the amount of the supported catalyst metal of 0.0005 to 0.1 mol
% relative to the support metal oxide in terms of metal. In the light of
prevention of carbon precipitation, the electronegativity is preferably 4
to 12 and the specific surface area of the catalyst is preferably 0.01 to
10 m2/g.

[0150] An electronegativity of a metal ion in the metal oxide is defined
by the following equation:

Xi=(1+2i)Xo [0151] wherein Xi represents an electronegativity
of the metal ion; Xo represents an electronegativity of the metal; and i
represents an electronic number of the metal ion.

[0152] When the metal oxide is a composite metal oxide, an average
electronegativity of the metal ions is used, and the value is the sum
total of electronegativity of the each metal ion in the composite metal
oxide multiplied by a mole fraction of each oxide.

[0154] Examples of the metal oxide in the catalyst include those
containing at least one metal such as Mg, Ca, Ba, Zn, Al, Zr and La. An
example of such a metal oxide is magnesia (MgO).

[0155] In a process in which methane and steam are reacted (steam
reforming), the reaction is represented by the following formula (I):

CH4+H2O⇄3H2+CO (i)

[0156] In a process in which methane and carbon dioxide are reacted
(CO2 reforming), the reaction is represented by the following
formula (ii):

CH4+CO2⇄2H2+2CO (ii)

[0157] In a process in which methane, steam and carbon dioxide are reacted
(steam/CO2 mixed reforming), the reaction is represented by the
following formula

3CH4+2H2O+CO2⇄8H2+4CO(iii)

[0158] In steam reforming using the catalyst as described above, a
reaction temperature is preferably 600 to 1200° C., more
preferably 600 to 1000° C., and a reaction pressure is preferably
0.098 MPaG to 3.9 MPaG, more preferably 0.49 MPaG to 2.9 MPaG (G
indicates that the value is a gauge pressure). When the steam reforming
is conducted with a fixed bed, a gas space velocity (GHSV) is preferably
1,000 to 10,000 hr-1, more preferably 2,000 to 8,000 hr-1. A
rate of steam to a carbon-containing starting material is preferably 0.5
to 2 moles, more preferably 0.5 to 1.5 moles, further preferably 0.8 to
1.2 moles of steam (H2O) per one mole of carbon in the
carbon-containing starting material (excluding CO2).

[0159] In CO2 reforming using the catalyst as described above, a
reaction temperature is preferably 500 to 1200° C., more
preferably 600 to 1000° C., and a reaction pressure is preferably
0.49 MPaG to 3.9 MPaG, more preferably 0.49 MPaG to 2.9 MPaG. When the
CO2 reforming is conducted with a fixed bed, a gas space velocity
(GHSV) is preferably 1,000 to 10,000 hr-1, more preferably 2,000 to
8,000 hr-1. A rate of CO2 to a carbon-containing starting
material is preferably 20 to 0.5 moles, more preferably 10 to 1 moles of
CO2 per one mole of carbon in the carbon-containing starting
material (excluding CO2).

[0160] When a carbon-containing starting material is reacted with a
mixture of steam and CO2 using the catalyst as described above to
produce a synthesis gas (i.e. steam/CO2 mixed reforming is
conducted), there are no restrictions to a ratio of steam to CO2,
but a ratio of H2O/CO2 (molar ratio) is generally 0.1 to 10. A
reaction temperature is preferably 550 to 1200° C., more
preferably 600 to 1000° C., and a reaction pressure is preferably
0.29 MPaG to 3.9 MPaG, more preferably 0.49 MPaG to 2.9 MPaG. When the
reaction is conducted with a fixed bed, a gas space velocity (GHSV) is
preferably 1,000 to 10,000 hr-1, more preferably 2,000 to 8,000
hr-1. A rate of steam to a carbon-containing starting material is
preferably 0.5 to 2 moles, more preferably 0.5 to 1.5 moles, further
preferably 0.5 to 1.2 moles of steam (H2O) per one mole of carbon in
the carbon-containing starting material (excluding CO2).

[0161] The catalyst described in JP-A-2000-288394 is composed of a
composite oxide having a composition represented by the following formula
(I), characterized in that M1 and Co are highly dispersed in the
composite oxide:

a1M1-b1Co-c1Mg-d1Ca-e1O (I)

[0162] wherein a1, b1, c1, d1 and e1 are mole
fractions, provided that a1+b1+c1+d1=1,
0.0001≦a1≦0.10, 0.0001≦b1≦0.20,
0.70≦(c1+d1)≦0.9998, 0<c1≦0.9998,
0≦d1<0.9998, and e1 is a number required for
maintaining the charge balance of the elements and oxygen;

[0163] M1 is at least one element selected from Group 6A elements,
Group 7A elements, Group 8 transition elements except Co, Group 1B
elements, Group 2B elements, Group 4B elements and lanthanoid elements in
the Periodic Table.

[0164] The catalyst described in JP-A-2000-469 is composed of a composite
oxide having a composition represented by the following formula (II),
characterized in that M2 and Ni are highly dispersed in the
composite oxide:

a2M2-b2Ni-c2Mg-d2Ca-e2O (II)

[0165] wherein a2, b2, c2, d2 and e2 are mole
fractions, provided that a2+b2+c2+d2=1,
0.0001≦a2≦0.10, 0.0001≦b2≦0.10,
0.80≦(c2+d2)≦0.9998, 0<c2≦0.9998,
0≦d2<0.9998, and e2 is a number required for
maintaining the charge balance of the elements and oxygen;

[0166] M2 is at least one element selected from Group 3B elements,
Group 4A elements, Group 6B elements, Group 7B elements, Group 1A
elements and lanthanoid elements in the Periodic Table.

[0167] These catalysts may be used in the same way as the catalyst
described in WO 98/46524.

[0168] A reforming reaction of a carbon-containing starting material, i.e.
a reaction for producing a synthesis gas, is not limited to the methods
as described above, and may be conducted in accordance with any of other
known methods. A reforming reaction of a carbon-containing starting
material may be conducted in various types of reactors, but is preferably
conducted in a fixed bed or a fluidized bed.

[0169] <Liquefied Petroleum Gas Production Process>

[0170] In a liquefied petroleum gas production process, a
lower-paraffin-containing gas, which comprises propane or butane as a
main component of the hydrocarbon contained therein, is produced from the
synthesis gas obtained in the synthesis gas production process as
described above, using a catalyst for producing a liquefied petroleum gas
according to the present invention. And then, water is separated from the
lower-paraffin-containing gas produced, as necessary, and subsequently a
low-boiling component having a lower boiling point or a lower sublimation
point than the boiling point of propane (unreacted starting materials,
hydrogen and carbon monoxide; by-products, carbon dioxide, ethane,
ethylene and methane; and so on) and a high-boiling component having a
higher boiling point than the boiling point of butane (by-products,
high-boiling paraffin gases; and so on) are separated from the
lower-paraffin-containing gas, as necessary, to obtain a liquefied
petroleum gas (LPG) comprising propane or butane as a main component. If
necessary, the gas may be pressurized and/or cooled so as to obtain a
liquefied petroleum gas.

[0171] In a liquefied petroleum gas production process, carbon monoxide
and hydrogen are reacted in the presence of the catalyst for producing a
liquefied petroleum gas of the present invention as described above, to
produce a paraffin comprising propane or butane as a main component,
preferably a paraffin comprising propane as a main component.

[0172] In this process, a gas fed into a reactor is the synthesis gas
produced in the synthesis gas production process as described above. The
gas fed into a reactor may be a gas obtained by adding carbon monoxide,
hydrogen and/or other components (carbon dioxide, water vapor, etc.), if
necessary, to the synthesis gas produced in the synthesis gas production
process as described above. Alternatively, the gas fed into a reactor may
be a gas obtained by separating a certain component, as necessary, from
the synthesis gas produced in the synthesis gas production process as
described above.

[0173] The reaction (LPG synthesis reaction) to form a
lower-paraffin-containing gas, using a catalyst according to the present
invention, may be conducted under the reaction conditions as described
above.

[0174] A lower-paraffin-containing gas produced in the liquefied petroleum
gas production process comprises a hydrocarbon containing propane or
butane as a main component. In the light of liquefaction properties, it
is preferable that the total content of propane and butane is higher in a
lower-paraffin-containing gas. According to the present invention, there
may be obtained a lower-paraffin-containing gas having a content of
propane and butane of 60% or more, preferably 70% or more, more
preferably 75% or more (including 100%) on the basis of carbon to the
hydrocarbon contained therein, in total.

[0175] Furthermore, a lower-paraffin-containing gas produced in the
liquefied petroleum gas production process preferably contains more
propane, as compared with butane, in the light of inflammability and
vapor pressure properties.

[0176] A lower-paraffin-containing gas produced in a liquefied petroleum
gas production process generally comprises water; a low-boiling component
having a lower boiling point or a lower sublimation point than the
boiling point of propane; and a high-boiling component having a higher
boiling point than the boiling point of butane. Examples of a low-boiling
component include ethane, methane and ethylene, which are by-products;
carbon dioxide which is formed by a shift reaction; and hydrogen and
carbon monoxide, which are unreacted starting materials. Examples of a
high-boiling component include high-boiling paraffins (e.g., pentane,
hexane and so on), which are by-products.

[0177] Accordingly, water, a low-boiling component and a high-boiling
component may be separated from a lower-paraffin-containing gas produced,
as necessary, to obtain a liquefied petroleum gas (LPG) comprising
propane or butane as a main component.

[0178] Separations of water, a low-boiling component and a high-boiling
component may be conducted in accordance with a known method.

[0179] Water may be separated by, for example, liquid-liquid separation.

[0180] A low-boiling component may be separated by, for example,
gas-liquid separation, absorption separation or distillation; more
specifically, gas-liquid separation at an ambient temperature under
increased pressure, absorption separation at an ambient temperature under
increased pressure, gas-liquid separation with cooling, absorption
separation with cooling, or combination thereof. Alternatively, for
separation of a low-boiling component, membrane separation or adsorption
separation may be conducted, and one of these separations in combination
with gas-liquid separation, absorption separation or distillation may be
conducted. A gas recovery process commonly employed in an oil factory
(described in "Oil Refining Processes", ed. The Japan Petroleum
Institute, Kodansha Scientific, 1998, pp. 28-32) may be employed for
separation of a low-boiling component.

[0181] A preferable method of separation of a low-boiling component may be
an absorption process in which a liquefied petroleum gas comprising
propane or butane as a main component is absorbed into an absorbent
liquid such as a high-boiling paraffin gas having a higher boiling point
than butane, and a gasoline.

[0182] A high-boiling component may be separated by, for example,
gas-liquid separation, absorption separation or distillation.

[0183] For consumer use, a content of a low-boiling component in the LPG
is preferably reduced to 5 mol % or less (including 0 mol %) by
separation, for example, in the light of safety in use.

[0184] The total content of propane and butane in the LPG thus produced
may be 90 mol % or more, more preferably 95 mol % or more (including 100
mol %).

[0185] According to the present invention, a low-boiling component
separated from the lower-paraffin-containing gas may be recycled as a
starting material for the synthesis gas production process.

[0186] A low-boiling component separated from the
lower-paraffin-containing gas comprises substances which may be used as
starting materials for a synthesis gas production process; for example,
methane, ethane, ethylene and so on. In addition, carbon dioxide in the
low-boiling component may be converted to a synthesis gas by a CO2
reforming reaction. Furthermore, a low-boiling component may comprise
hydrogen and carbon monoxide, which are unreacted starting materials.
Accordingly, the low-boiling component separated from the
lower-paraffin-containing gas may be recycled as a starting material for
a synthesis gas production process, leading to an increase in
productivity per starting material.

[0187] The whole low-boiling components separated from a
lower-paraffin-containing gas may be recycled to a synthesis gas
production process. Alternatively, part of the low-boiling components may
be removed outside the system, while the rest may be recycled to a
synthesis gas production process. A desired component may be separated
from the low-boiling components and recycled to a synthesis gas
production process.

[0188] In a synthesis gas production process, a content of a low-boiling
component in a gas fed into a reformer (i.e. reactor), in other words, a
content of a recycled material may be determined as appropriate, and it
may be, for example, 40 to 75 mol %.

[0189] Any known technique, e.g. providing a recycle line with a
pressurization means may be employed as appropriate, to recycle a
low-boiling component.

EXAMPLES

[0190] The following will describe the present invention in more detail
with reference to Examples. However, the present invention is not limited
to these Examples.

Example 1

Preparation of Catalyst

[0191] A Cu--Zn--Al--Cr composite oxide (average particle size: about 0.35
mm to about 0.7 mm) was used as a Cu--Zn-based methanol synthesis
catalyst, which is a methanol synthesis catalyst component.

[0192] As a Cu-supported β-zeolite, which is a zeolite catalyst
component, 0.5 wt % of Cu was supported on a commercially available
proton-type β-zeolite with a SiO2/Al2O3 ratio of 37
(produced by ZEOLYST INTERNATIONAL Inc.) by an ion exchange method as
follows, to prepare a Cu-supported β-zeolite (average particle size:
about 0.35 mm to about 0.7 mm).

[0193] First, 0.57 g of Cu(NO3)2.3H2O was dissolved in 150
mL of ion-exchanged water to prepare a Cu-containing solution
(concentration: 0.067 wt %). And then, 2.0 g of βzeolite was added
to the resulting Cu-containing solution, and the mixture was heated and
stirred at 65° C. for 8 hours. The resulting material was
filtrated and washed with ion-exchanged water three times.

[0194] The Cu-supported β-zeolite thus obtained was dried at
120° C. for 10 hours, and then calcined at 500° C. for 4
hours. Subsequently, the Cu-supported β-zeolite was mechanically
pulverized, and molded by a tablet-compression and sized to give a
Cu-supported β-zeolite having an average particle size of 0.35 to
0.7 mm.

[0195] And then, the Cu--Zn-based methanol synthesis catalyst
(hereinafter, also referred to as "Cu--Zn") and the Cu-supported
β-zeolite thus prepared (hereinafter, also referred to as "0.5%
Cu-β-37") were homogeneously mixed at a weight ratio of Cu--Zn:0.5%
Cu-β-37=1:1, to give a catalyst for producing a liquefied petroleum
gas.

[0196] (Production of LPG)

[0197] In a tubular reactor with an inner diameter of 6 mm was placed 1 g
of the catalyst thus prepared. The catalyst was subjected to reduction
treatment under a hydrogen stream at 300° C. for 3 hours prior to
the reaction.

[0198] After reduction treatment of the catalyst, a starting gas having
the composition of H2:CO:Ar=64.56:32.4:3.0 (molar ratio) was passed
through the catalyst layer at various reaction temperatures (from
280° C. to 340° C.) shown in FIG. 2, a reaction pressure of
2.0 MPa, and a W/F of 8.9 μl/mol, to carry out the LPG production
reaction. A gas chromatography was used for the analysis of the product.

[0199] FIG. 2 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon at a reaction
time of 3 hours. The catalyst exhibited higher catalytic activity and
higher selectivity for LPG, particularly at low temperatures.

Example 2

Preparation of Catalyst

[0200] A catalyst was prepared in the same way as Example 1, except that a
proton-type β-zeolite with a SiO2/Al2O3 ratio of 350
(produced by ZEOLYST INTERNATIONAL Inc.) was used as a support
(β-zeolite) for the Cu-supported β-zeolite. Hereinafter, the
Cu-supported β-zeolite thus prepared was also referred to as "0.5%
Cu-β-350".

[0201] (Production of LPG)

[0202] Using the prepared catalyst, the LPG production reaction and gas
chromatographic analysis of the product were carried out in the same way
as Example 1.

[0203] FIG. 3 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon at a reaction
time of 3 hours. The catalyst comprising the β-zeolite with a
SiO2/Al2O3 ratio of 350 exhibited lower catalytic activity
and higher production of higher hydrocarbon (C5+) in particular, as
compared with the catalyst comprising the fβ-zeolite with a
SiO2/Al2O3 ratio of 37.

Example 3

Preparation of Catalyst

[0204] A catalyst was prepared in the same way as Example 1, except that
the amount of Cu in the Cu-supported β-zeolite was 5.0 wt %.
Hereinafter, the Cu-supported β-zeolite thus prepared was also
referred to as "5.0% Cu/β-37".

[0205] (Production of LPG)

[0206] Using the prepared catalyst, the LPG production reaction and gas
chromatographic analysis of the product were carried out in the same way
as Example 1 at various reaction temperatures (from 267° C. to
330° C.), a reaction pressure of 2.0 MPa, and a W/F of 8.9 gh/mol,
except that the catalyst was subjected to reduction treatment at
300° C. for 4 hours.

[0207] FIG. 4 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon at a reaction
time of 3 hours. The catalyst exhibited higher conversion of carbon
monoxide and higher selectivity for LPG as the reaction temperature
increased, and very low production of methane at high temperatures.

Example 4

Preparation of Catalyst

[0208] A catalyst was prepared in the same way as Example 1, except that
the amount of Cu in the Cu-supported β-zeolite was 10 wt %.
Hereinafter, the Cu-supported β-zeolite thus prepared was also
referred to as "10% Cu/β-37".

[0209] (Production of LPG)

[0210] Using the prepared catalyst, the LPG production reaction and gas
chromatographic analysis of the product were carried out in the same way
as Example 1 at various reaction temperatures (from 273° C. to
335° C.), a reaction pressure of 2.0 MPa, and a W/F of 8.9 gh/mol,
except that the catalyst was subjected to reduction treatment at
300° C. for 4 hours.

[0211] FIG. 5 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon at a reaction
time of 3 hours. The catalyst wherein the amount of Cu in the
Cu-supported β-zeolite was 10 wt % exhibited further higher
selectivity for LPG, although the conversion of carbon monoxide was not
enhanced, and very low production of methane.

Example 5

Production of LPG

[0212] Using the catalyst (Cu--Zn+5.0% Cu/β-37) prepared in the same
way as Example 3, the LPG production reaction and gas chromatographic
analysis of the product were carried out in the same way as Example 3 at
various reaction pressures (from 2.0 MPa to 5.0 MPa), except that the
reaction temperature was 300° C.

[0213] FIG. 6 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon at a reaction
time of 3 hours. The catalyst exhibited higher conversion of carbon
monoxide and lower selectivity for LPG as the reaction pressure
increased.

Example 6

Production of LPG

[0214] Using the catalyst (Cu--Zn+5.0% Cu/β-37) prepared in the same
way as Example 3, the LPG production reaction and gas chromatographic
analysis of the product were carried out in the same way as Example 3 at
various W/Fs (from 2.6 gh/mol to 15.0 gh/mol), except that the reaction
temperature was 300° C.

[0215] FIG. 7 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon at a reaction
time of 3 hours. The catalyst exhibited much higher conversion of carbon
monoxide and higher selectivity for LPG as the contact time between the
starting gas and the catalyst was longer.

Example 7

Production of LPG

[0216] Using the catalyst (Cu--Zn+5.0% Cu/β-37) prepared in the same
way as Example 3, the LPG production reaction and gas chromatographic
analysis of the product were carried out in the same way as Example 3,
except that the reaction temperature was 300° C. (Reaction
conditions: reaction temperature: 300° C.; reaction pressure: 2.0
MPa; W/F: 8.9 gh/mol).

[0217] FIG. 8 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst exhibited higher catalytic activity and higher selectivity for
LPG, and less deterioration over time and higher stability.

Example 8

Production of LPG

[0218] Using the catalyst (Cu--Zn+10% Cu/β-37) prepared in the same
way as Example 4, the LPG production reaction and gas chromatographic
analysis of the product were carried out in the same way as Example 7,
except that the catalyst was subjected to reduction treatment at
290° C. for 4 hours.

[0219] FIG. 9 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst wherein the amount of Cu in the Cu-supported β-zeolite was
10 wt % exhibited higher initial activity but the catalytic activity
rapidly decreased, as compared with the catalyst wherein the amount of Cu
in the Cu-supported β-zeolite was 5 wt %.

Example 9

Preparation of Catalyst

[0220] A catalyst was prepared in the same way as Example 1, except that
the amount of Cu in the Cu-supported β-zeolite was 2.0 wt %.
Hereinafter, the Cu-supported β-zeolite thus prepared was also
referred to as "2.0% Cu/13-37".

[0221] (Production of LPG)

[0222] Using the prepared catalyst (Cu--Zn+2.0% Cu/β-37), the LPG
production reaction and gas chromatographic analysis of the product were
carried out in the same way as Example 7, except that the catalyst was
subjected to reduction treatment at 290° C. for 4 hours.

[0223] FIG. 10 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst wherein the amount of Cu in the Cu-supported β-zeolite was
2 wt % exhibited high stability but lower selectivity for LPG, as
compared with the catalyst wherein the amount of Cu in the Cu-supported
β-zeolite was 5 wt %.

Example 10

Preparation of Catalyst

[0224] A catalyst was prepared in the same way as Example 1, except that a
Cu-supported β-zeolite [hereinafter, also referred to as "(5.0%
Cu+2.5% Zn)/β-37"] in which 5.0 wt % of Cu and 2.5 wt % of Zn were
supported on a β-zeolite with a SiO2/Al2O3 ratio of
37 was used as a zeolite catalyst component.

[0226] First, 0.57 g of Cu(NO3)23H2O and 0.22 g of
Zn(NO3)2.6H2O were dissolved in 150 mL of ion-exchanged
water to prepare a Cu, Zn-containing solution (Cu concentration: 0.067 wt
%; Zn concentration: 0.034 wt %). And then, 2.0 g of proton-type
β-zeolite with a SiO2/Al2O3 ratio of 37 (produced by
ZEOLYST INTERNATIONAL Inc.) was added to the resulting Cu, Zn-containing
solution, and the mixture was heated and stirred at 65° C. for 8
hours. The resulting material was filtrated and washed with ion-exchanged
water three times.

[0227] The Cu-supported β-zeolite thus obtained was dried at
120° C. for 10 hours, and then calcined at 500° C. for 4
hours. Subsequently, the Cu-supported β-zeolite was mechanically
pulverized, and molded by a tablet-compression and sized to give a
Cu-supported β-zeolite having an average particle size of 0.35 to
0.7 mm.

[0228] (Production of LPG)

[0229] Using the prepared catalyst [Cu--Zn+(5.0% Cu+2.5% Zn)/β-37],
the LPG production reaction and gas chromatographic analysis of the
product were carried out in the same way as Example 7, except that the
catalyst was subjected to reduction treatment at 280° C. for 4
hours, and the reaction temperature was 290° C.

[0230] FIG. 11 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst wherein Zn in addition to Cu was supported on the 62-zeolite did
not exhibit a remarkable effect and the catalytic activity relatively
rapidly decreased.

Example 11

Preparation of Catalyst

[0231] A catalyst was prepared in the same way as Example 1, except that a
Cu-supported β-zeolite [hereinafter, also referred to as "(5.0%
Cu+2.5% Zr)/β-37"] in which 5.0 wt % of Cu and 2.5 wt % of Zr were
supported on a β-zeolite with a SiO2/Al2O3 ratio of
37 was used as a zeolite catalyst component.

[0233] First, 0.57 g of Cu(NO3)2.3H2O and 0.147 g of
ZrO(NO3)2 were dissolved in 150 mL of ion-exchanged water to
prepare a Cu, Zr-containing solution (Cu concentration: 0.067 wt %; Zr
concentration: 0.034 wt %). And then, 2.0 g of proton-type β-zeolite
with a SiO2/Al2O3 ratio of 37 (produced by ZEOLYST
INTERNATIONAL Inc.) was added to the resulting Cu, Zr-containing
solution, and the mixture was heated and stirred at 65° C. for 8
hours. The resulting material was filtrated and washed with ion-exchanged
water three times.

[0234] The Cu-supported β-zeolite thus obtained was dried at
120° C. for 10 hours, and then calcined at 500° C. for 4
hours. Subsequently, the Cu-supported β-zeolite was mechanically
pulverized, and molded by a tablet-compression and sized to give a
Cu-supported β-zeolite having an average particle size of 0.35 to
0.7 mm.

[0235] (Production of LPG)

[0236] Using the prepared catalyst [Cu--Zn+(5.0% Cu+2.5% Zr)/β-37],
the LPG production reaction and gas chromatographic analysis of the
product were carried out in the same way as Example 7, except that the
catalyst was subjected to reduction treatment at 280° C. for 4
hours, and the reaction temperature was 290° C.

[0237] FIG. 12 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst wherein Zr in addition to Cu was supported on the β-zeolite
exhibited higher stability.

Example 12

Preparation of Catalyst

[0238] A catalyst was prepared in the same way as Example 11, except that
a Cu--Zn-based methanol synthesis catalyst [hereinafter, also referred to
as "Cu--Zn+2.5% Cr"] in which 2.5 wt % of Cr was supported on a self-made
Cu--Zn-based methanol synthesis catalyst (Cu--Zn--Al composite oxide) by
an impregnation method was used as a methanol synthesis catalyst
component.

[0240] First, 0.58 g of Cr(NO3)3.9H2O was dissolved in 3.5
mL of ion-exchanged water to prepare a Cr-containing solution
(concentration: 2.1 wt %). And then, 3 g of Cu--Zn-based methanol
synthesis catalyst (Cu--Zn--Al composite oxide) was added to the
resulting Cr-containing solution, and impregnated with the Cr-containing
solution for 3 hours. The resulting Cu--Zn-based methanol synthesis
catalyst impregnated with the Cr-containing solution was dried at
120° C. for 10 hours, and then calcined at 500° C. for 4
hours. Subsequently, the Cr-supported Cu--Zn-based methanol synthesis
catalyst was mechanically pulverized, and molded by a tablet-compression
and sized to give a Cr-supported Cu--Zn-based methanol synthesis catalyst
having an average particle size of 0.35 to 0.7 mm.

[0241] (Production of LPG)

[0242] Using the prepared catalyst [(Cu--Zn+2.5% Cr)+(5.0% Cu+2.5%
Zr)/β-37], the LPG production reaction and gas chromatographic
analysis of the product were carried out in the same way as Example 11.

[0243] FIG. 13 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst wherein Cr was supported on the Cu--Zn-based methanol synthesis
catalyst did not exhibit a remarkable effect and the catalytic activity
rapidly decreased.

Example 13

Preparation of Catalyst

[0244] A catalyst was prepared in the same way as Example 11, except that
a Cu--Zn-based methanol synthesis catalyst [hereinafter, also referred to
as "Cu--Zn+2.5% Zr" in which 2.5 wt % of Zr was supported on a self-made
Cu--Zn-based methanol synthesis catalyst (Cu--Zn--Cr composite oxide) by
an impregnation method was used as a methanol synthesis catalyst
component.

[0246] First, 0.147 g of ZrO(NO3)2.xH2O was dissolved in
2.5 mL of ion-exchanged water to prepare a Zr-containing solution
(concentration: 2.0 wt %). And then, 2 g of Cu--Zn-based methanol
synthesis catalyst (Cu--Zn--Cr composite oxide) was added to the
resulting Zr-containing solution, and impregnated with the Zr-containing
solution for 3 hours. The resulting Cu--Zn-based methanol synthesis
catalyst impregnated with the Zr-containing solution was dried at
120° C. for 10 hours, and then calcined at 500° C. for 4
hours. Subsequently, the Zr-supported Cu--Zn-based methanol synthesis
catalyst was mechanically pulverized, and molded by a tablet-compression
and sized to give a Zr-supported Cu--Zn-based methanol synthesis catalyst
having an average particle size of 0.35 to 0.7 mm.

[0247] (Production of LPG)

[0248] Using the prepared catalyst [(Cu--Zn+2.5% Zr)+(5.0% Cu+2.5%
Zr)/β-37], the LPG production reaction and gas chromatographic
analysis of the product were carried out in the same way as Example 11.

[0249] FIG. 14 shows the conversion of carbon monoxide into hydrocarbon
(CH), the conversion of carbon monoxide into carbon dioxide by shift
reaction, and the composition of the produced hydrocarbon over time. The
catalyst wherein Zr was supported on the Cu--Zn-based methanol synthesis
catalyst exhibited much higher stability. The catalyst exhibited higher
catalytic activity and higher selectivity for LPG, and much less
deterioration over time.

[0250] The results [the conversion of carbon monoxide into hydrocarbon,
the conversion of carbon monoxide into carbon dioxide by shift reaction,
and the composition of the produced hydrocarbon] at a reaction time of 50
hours for mixed catalysts of Cu--Zn-based methanol synthesis catalysts
and Cu-supported β-zeolites (SiO2/Al2O3 ratio: 37)
[Examples 7 to 13] are shown in Table 1.

[0251] In all Examples, the LPG production reaction produces substantially
no DME.

[0252] As described above, a catalyst for producing a liquefied petroleum
gas according to the present invention has a longer catalyst life with
less deterioration over time, and enables the production of a hydrocarbon
containing propane or butane as a main component, i.e. a liquefied
petroleum gas (LPG), by reacting carbon monoxide and hydrogen, with high
activity, high selectivity and high yield. Therefore, when using the
catalyst according to the present invention, LPG may be stably produced
from a carbon-containing starting material such as a natural gas or a
synthesis gas for a long period with high activity, high selectivity and
high yield. Moreover, the catalyst according to the present invention
does not comprise high-priced Pd, and therefore the catalyst is more
inexpensive than conventional catalysts.